I'm having the same problem using Cacko 1.23 on my 860. I'm guessing theres something dumb going on, like not authenticating with the outbound proxy... I'm not sure I'm going to have any time to sniff the packets and look around, but I'd LOVE to have a fully functioning phone in my zaurus ;-)
UPDATE: I stayed up and played with this late night. Fortunately, KPhone and X-Lite have debug consoles (well, kphone can be called from the command prompt and outputs to stderr anyway) that issue very similar output. Here's what I've learned:
Apparently, when you issue an invitation (calling someone), both SIP clients do so without any authentication information. Broadvoice's service responds with "401 Unauthorized", but provides some information about how you should authenticate yourself (Realm to use, md5 hash, etc). At this point, X-Lite responds with authentication information (that looks VERY SIMILAR to the auth info kphone sends when you register (at program launch) ), and kphone just gives up, returning the "Unauthorized" message to the user.
I found something in a forum here:
http://sourceforge.net/mailarchive/message...msg_id=12009583that seems to say the problem is happening because kphone can't authenticate with a realm other than the "Host part of SIP URL" (sip.broadvoice.com). I assume this means we're stuck with incoming only until either a) KPhone is updated to work with this, or broadvoice changes their authentication Realm for outgoing calls to "sip.broadvoice.com".